Oil Separator Built-In Compressor

ABSTRACT

Provided is an oil separator built-in compressor, which prevents a drop in the separating ability of an oil separator while reducing a pressure loss in a communication hole formed between a discharge chamber and an oil separation chamber and which also considers the working feasibility of a casing. The oil separator built-in compressor comprises: a separation chamber arranged adjacent to the discharge chamber and formed entirely thereof into a space in order to separate an oil-containing gas being introduced, centrifugally into gas and oil so that the separated oil flows downward whereas the separated gas is released upward; and the communication hole formed between the discharge chamber and the separation chamber in order to introduce the oil-containing gas from the discharge chamber into the separation chamber. The oil separator built-in compressor is characterized in that the oil separator is formed of the joint structure of two members for constituting the compressor, and in that a portion of the inner wall face of the communication hole is formed at a position farther from the joining face of the joint structure than the inner wall face of the separation chamber.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to an oil separator built-in compressor, and specifically relates to an oil separator built-in compressor which is designed to achieve simplification and downsizing of an oil separator mechanism, reduction of the number of parts, ease of assembling and low pressure loss.

BACKGROUND ART OF THE INVENTION

Patent document 1 discloses a conventional oil separator built-in compressor, which incorporates an centrifugal oil separator in a compressor which is installed in a refrigeration system for automotive air conditioning devices. In a conventional oil separator built-in compressor, when gas including oil in discharge chamber 2 is introduced into oil separation chamber 7 through communication hole 18 and the gas whirls along an inner wall surface of oil separation chamber 7, centrifugal force is generated so as to separate the gas and the oil, as shown in FIG. 6 with an example of cross section structure of conventional oil separation chamber 7. In Patent document 1, oil separation chamber 7 is formed with a structure where fixed scroll member 5 and casing 6 are put together on joining face 11. In FIG. 6( b), symbol 18 a indicates an upper communication hole as one of communication holes which are arrayed in a vertical direction. On the other hand, symbol 18 b indicates a lower communication hole.

-   Patent document 1: JP2008-82238-A

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

They are trying to reduce pressure loss by extending the cross section of the communication hole in order to meet the latest needs of greater discharge volume of compressors. However, if the communication hole is simply extended with the above-described conventional structure, the following trouble might occur.

When a plural of communication holes 18 are formed in a conventional oil separator built-in compressor having the above-described structure, the extension of cross section of communication holes 18 might make walls between adjacent communication holes 18 too thin, so as to make it difficult to form casing 6 by casting or forging. In order to keep sufficient wall thickness of the walls between adjacent communication holes, the position of lower communication hole 18 b may be lowered, for example. However, if lower communication hole 18 b is located at lower position below oil separation chamber 7, sufficient gas whirling region to separate the oil becomes smaller, and the oil separation ability of the oil separator may decrease.

Focusing on the above-described problems, an object of the present invention is to provide an oil separator built-in compressor which can reduce the pressure loss at the communication holes between the discharge chamber and the oil separation chamber and of which casing can be easily formed.

Means for Solving the Problems

In order to achieve the above-described object, an oil separator built-in compressor according to the present invention is an oil separator built-in compressor comprising:

a separation chamber which is arranged adjacent to a discharge chamber and an inside of which is formed entirely into a space so as to separate an oil-containing gas introduced, centrifugally into gas and oil so that the separated oil flows downward whereas the separated gas is released upward; and

a communication hole, which is formed between the discharge chamber and the separation chamber and which introduces the oil-containing gas from the discharge chamber into the separation chamber,

characterized in that an oil separator is formed from a joint structure of two members for constituting the compressor, and in that a portion of the inner wall surface of the communication hole is formed at a position farther from the joining face of the joint structure than the inner wall surface of the separation chamber.

The oil separator built-in compressor according to the present invention makes it possible to constitute the separation chamber of the oil separator with a simple and compact structure because the oil separator is formed with a joint structure of two members in the oil separator built-in compressor having a communication hole which is formed between the discharge chamber and the separation chamber and which introduces the oil-containing gas from the discharge chamber into the separation chamber. It also makes it possible to reduce the pressure loss because the portion of the inner wall surface of the communication hole is formed at a position farther from the joining face of the joint structure than the inner wall surface of the separation chamber so that the communication hole is formed at a conventional position to maintain the separation ability at a predetermined level and the cross section of the communication hole has been enlarged.

In the present invention, it is desirable that the communication hole is formed at a position farthest from the joining face of the joint structure. Here, to be farthest from the joining face means that the distance from the joining face is the longest in the member on which the communication hole is machined. Such formed communication hole makes it possible that dead spaces of gas flow are not likely to appear when the oil-containing gas is introduced from the communication hole into the separation chamber, so that the gas which is flowed into the separation chamber is given superior centrifugal separation performance.

In addition, the present invention shows a great advantage particularly if a plural of the communication holes are arrayed in the vertical direction. In other words, machining the casing by casting and forging becomes less difficult because the pressure loss can be reduced without changing the array pitch of adjacent communication holes when the cross section of communication holes arrayed in the vertical direction is enlarged.

Further, the communication holes can be formed with a structure where the communication holes are opened in the same direction toward the separation chamber. In such a case, even if the amount of gas blown into the oil separation chamber is relatively large, each direction for blowing of gas through each communication holes can be optimized, so that centrifugal separation is performed efficiently in the separation chamber and efficiently introduces separated oil into the oil storage chamber. Alternatively, the structure can be a structure where the communication holes are opened in different directions toward the separation chamber. In such a case, each direction of gas blowing into the oil separation chamber can be set at a different angle according to each communication hole. Therefore the gas blowing direction can be set as suitable to the shape of the oil separation chamber, so that the gas blown from each communication hole is efficiently separated centrifugally to introduce the efficiently separated oil into the oil storing chamber.

Further, it is desirable that the communication holes are formed so as to make an array pitch P [mm] of the communication holes and a vertical width W [mm] of each communication hole satisfy the following formula.

W+2≦P≦W+7

The above-described formula has the following meaning. It means that the array pitch is preferably not less than 2 mm in addition to vertical width W of each communication hole from a viewpoint of casting process of the casing. In other words, the wall thickness is preferably not less than 2 mm between adjacent communication holes, and the array pitch is preferably not more than 7 mm in addition to vertical width W of each communication hole so as to sufficiently achieve the air curtain effect in the separation chamber. Here, the air curtain effect is an effect to prevent the separated oil from flowing upward together with an upflow of gas by a twisting curtain-like flow of stable gas flow along the inner wall of the separation chamber.

More concretely, it is possible that the oil separator built-in compressor according to the present invention has the oil separator which has a lower hole to deliver the oil separated in the separation chamber into an oil storing chamber located below the separation chamber. Because such a lower hole can be formed with a joint structure of two members composing the compressor, great improvement of productivity and cost reduction are expected.

Because the oil separator built-in compressor of which the oil separator is formed with a joint structure of two members is made of small number of component parts and has no portion to be machined, the shape of the separation chamber can be extremely freely formed. Therefore, the separation chamber can be formed into a cylindrical shape of which bus part extends linearly, and alternatively into a cylindrical shape, such as a donut shape as a whole (a partial donut shape), of which bus part curves.

Though the cross-sectional shape of the curving cylindrical shape is preferably a substantively perfect circle, the joint structure of two members may have either a step on the inner surface of the cylindrical shape or a difference of curvature between the arcs in the cross-section of the cylindrical shape of members forming the inner surface of the cylindrical shape. Further, there can be a circumferential difference of inner surface between both members forming the inner surface of the cylindrical shape. Furthermore, there can be a differential depth of circular groove in the cross-section of the cylindrical shape between both members forming the inner surface of the cylindrical shape.

The oil separator built-in structure of the present invention is applicable to all types of compressors substantively, and is specifically suitable for a scroll type compressor. A structure, where one of the two members is a fixed scroll forming member and the other is a compressor casing, can be applied to a scroll type compressor, for example.

The oil separator built-in compressor according to the present invention can be used as a compressor for an automotive air conditioning system because the oil separator is formed with a joint structure of two members for constituting the compressor and therefore is easy to reduce its size and weight.

Effect According to the Invention

Thus, the oil separator built-in compressor according to the present invention makes it possible that the cross-section of the communication hole is enlarged so as to reduce pressure loss without changing the array of communication hole in a conventional structure and that component parts, such as casing provided with a communication hole can be easily formed by casting or forging while desirable centrifugal separation performance and processing characteristics can be maintained. Furthermore, casting and forging of which desirable separation performance and processing characteristics have been maintained can be performed more surely, when the array pitch of the communication holes is set within a predetermined range. In addition, the oil separator built-in compressor of the present invention is suitably used as a compressor for an automotive air conditioning system because the oil separator has a joint structure which is easy to reduce its size and weight.

BRIEF EXPLANATION OF THE DRAWINGS

FIG. 1 is a longitudinal sectional view showing a joint structure of an oil separator built-in compressor according to an embodiment of the present invention.

FIG. 2 is a cross sectional view showing the compressor shown in FIG. 1, where (a) shows a cross section viewed in A-A direction and (b) shows a cross section viewed in B-B direction.

FIG. 3 is a cross sectional view showing a separation chamber of the compressor shown in FIG. 2, where (a) shows a cross section of the separation chamber viewed from the upper side of FIG. 2 and (b) shows a cross section of the communication hole viewed from the right side thereof.

FIG. 4 is an explanatory diagram for array pitch P of communication holes and vertical width W of each communication hole, where (a) shows an enlarged neighborhood of the separation chamber in FIG. 2( b) and (b) is one corresponding to FIG. 3( b).

FIG. 5 is an explanatory diagram for whirling gas flow generated in a separation chamber of oil separator built-in compressor according to the present invention, where (a) shows a case where upper and lower communication holes are sufficiently close and (b) shows another case where upper and lower communication holes are sufficiently apart.

FIG. 6 is a cross sectional view showing a separation chamber of a conventional oil separator built-in compressor, where (a) shows a cross section of a separation chamber and (b) shows a cross section of a communication hole viewed from the right side.

EXPLANATION OF SYMBOLS

-   1: oil separator built-in compressor -   2: discharge chamber -   3: second discharge chamber -   4: oil trap chamber -   5 fixed scroll member -   6: casing -   7: separation chamber -   8, 18: communication hole -   8 a, 18 a: upper communication hole -   8 b, 18 b: lower communication hole -   9: lower side hole -   10: gas passageway -   11: joining face -   12: oil separator

THE BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, desirable embodiments will be explained as referring to figures.

FIG. 1 is a longitudinal sectional view showing a joint structure of an oil separator built-in compressor according to an embodiment of the present invention. Compressor 1 is a scroll type compressor where discharge chamber 2, second discharge chamber 3 and oil trap chamber 4 are formed with a joint structure between fixed scroll member 5 and casing 6.

FIG. 2 shows a cross section of compressor 1 shown in FIG. 1, where (a) is a sectional view in A-A direction of FIG. 1 and (b) is a sectional view in B-B direction of FIG. 1. As shown in FIG. 2( b), upper communication hole 8 a and lower communication hole 8 b are formed to connect discharge chamber 2 and separation chamber 7 by a joint structure between fixed scroll member 5 shown in FIG. 2( a) and casing 6 side which has been machined for forming communication hole 8. On the other hand, lower hole 9 is formed to connect separation chamber 7 and oil trap chamber 4 by a joint structure between casing 6 side and fixed scroll member 5 side which have been machined for forming lower hole 9. Oil-containing compressed gas, which is compressed with a compression mechanism and is introduced in discharge chamber 7, is introduced through communication hole 8 into separation chamber 7 as forming a whirling flow along an inner wall of separation chamber 7. Preferably, the whirling flow forms a whirling flow which moves down along the inner wall of separation chamber 7 and the oil in the gas is separated from the gas by centrifugal separation with the whirling flow. The separated oil moves down on the inner wall of separation chamber 7 through lower hole 9 and is trapped in oil trap chamber 4. On the other hand, the gas separated from the oil is introduced via gas passageway 10 into second discharge chamber 3 as forming upward flow in the center of cross section of separation chamber 7, so as to be discharged through a discharge port. In this way, compressor 1 incorporates oil separator 12 provided with separation chamber 7, communication hole 8, lower hole 9 and oil trap chamber 4.

FIG. 3 shows a section of separation chamber 7 of compressor 1 shown in FIG. 2, where (a) is a cross sectional view of separation chamber 7 viewed from the top side of FIG. 2 and (b) is a cross sectional view of communication hole 8 viewed from the right side of (a). As to communication hole 8 connecting discharge chamber 2 and separation chamber 7, a part of the communication hole inner wall surface is formed at a position farther from joining face 11 than the inner wall surface of separation chamber 7, unlike the conventional compressor shown in FIG. 6. Communication hole is apertured at a position which is the farthest from joining face 11 of the above-described joint structure in the inner wall surface of separation chamber 7. Here, being the farthest from joining face 11 means that a distance from the joining face 11 is the longest in a member where a portion for forming communication hole 8 is machined. In FIG. 3, it corresponds to points Q1 and Q2, positions of which distances are the longest from joining face 11 at the side of casing 6 where the portion to form communication hole 8 is supposed to be machined. Thus communication hole 8 is formed as digging into the inner wall surface of separation chamber 7 in the neighborhood of points Q1, Q2. Therefore, cross-sectional area of each communication hole 8 a, 8 b can be scaled up without changing the vertical position of communication holes 8 a and 8 b arrayed as shown in FIG. 2( b), so that pressure loss can be reduced.

FIG. 4 is an explanatory diagram for array pitch P of communication holes 8 and vertical width W of each communication hole 8, where (a) shows an enlarged neighborhood of separation chamber 7 in FIG. 2( b) and (b) is one corresponding to FIG. 3( b). It can be found from the Figs that when P equals to W+2 wall thickness between adjacent communication holes 8 will be 2 mm and that when P equals to W+7 wall thickness between adjacent communication holes 8 will be 7 mm. It is preferable that the formula P≧W+2 is satisfied from the viewpoint of machining of casing 6 on which communication hole 8 is formed. On the other hand, it is preferable that the formula P≦W+7 is satisfied from the viewpoint of advancing an air curtain effect.

FIG. 5 is an explanatory diagram for whirling gas flow generated in separation chamber 7 of oil separator built-in compressor according to the present invention, where (a) shows a case where upper communication hole 8 a and lower communication hole 8 b are sufficiently close, and (b) shows another case where upper communication hole 8 a and lower communication hole 8 b are sufficiently apart. In FIG. 5( a) oil-containing gas introduced from lower communication hole 8 b is whirling toward lower hole 9 below separation chamber 7 as being affected by an air curtain effect which is generated by the whirling flow of oil-containing gas introduced from upper communication hole 8 a. On the other hand, in FIG. 5( b) whirling flow is not strong enough to generate sufficient air curtain effect. Therefore some oil-containing gas introduced from lower communication hole 8 b into separation chamber 7 whirls toward the side of gas passageway 10 above separation chamber 7 in vain, so that the oil separation performance of oil separator 12 deteriorates. Thus the size of array pitch P of communication hole 8 affects separation performance of oil separator 12. As explained with FIG. 4, when array pitch P is defined as satisfying the relation of P≦W+7, air curtain effect as shown in FIG. 5( b) rather than FIG. 5( a) is achieved so as to ensure the separation performance of oil separator 12.

INDUSTRIAL APPLICATIONS OF THE INVENTION

The composition of an oil separator built-in compressor according to the present invention is applicable to any type of compressors incorporating an oil separator, and suitable for a scroll-type compressor. 

1. An oil separator built-in compressor comprising: a separation chamber which is arranged adjacent to a discharge chamber and an inside of which is formed entirely into a space so as to separate an oil-containing gas introduced, centrifugally into gas and oil so that a separated oil flows downward whereas a separated gas is released upward; and a communication hole, which is formed between said discharge chamber and said separation chamber and which introduces said oil-containing gas from said discharge chamber into said separation chamber, characterized in that an oil separator is formed from a joint structure of two members for constituting a compressor, and in that a portion of an inner wall surface of said communication hole is formed at a position farther from a joining face of said joint structure than said inner wall surface of said separation chamber.
 2. The oil separator built-in compressor according to claim 1, wherein said communication hole is formed at a position farthest from said joining face of said joint structure.
 3. The oil separator built-in compressor according to claim 1, wherein a plural of said communication holes are arrayed in a vertical direction.
 4. The oil separator built-in compressor according to claim 3, wherein said communication holes are opened in a same direction toward said separation chamber.
 5. The oil separator built-in compressor according to claim 3, wherein said communication holes are opened in different directions toward said separation chamber.
 6. The oil separator built-in compressor according to claim 3, wherein said communication holes are formed so as to make an array pitch P [mm] of said communication holes and a vertical width W [mm] of each communication hole satisfy a following formula: W+2≦P≦W+7.
 7. The oil separator built-in compressor according to claim 1, provided with said oil separator which has a lower hole to deliver said oil separated in said separation chamber into an oil storing chamber located below said separation chamber.
 8. The oil separator built-in compressor according to claim 1, wherein said separation chamber is formed into a cylindrical shape of which bus part extends linearly.
 9. The oil separator built-in compressor according to claim 1, wherein said separation chamber is formed into a cylindrical shape of which bus part curves.
 10. The oil separator built-in compressor according to claim 1, wherein a compressor is a scroll type compressor, wherein one of said two members is a fixed scroll forming member and another is a compressor casing.
 11. The oil separator built-in compressor according to claim 1, wherein a compressor is a compressor for an automotive air conditioning system. 